Question

Average Zinc content of mineral soils varies from:

• A. 10 to 330 ppm
• B. 1 to 30 ppm
• C. 350 to 500 ppm
• D. 500 to 1000 ppm

Hint:

Do not confuse total soil content with available soil content.
Total Zinc is 10--330 ppm, whereas available (DTPA-extractable) zinc is critical when it drops below 0.6 ppm (deficiency threshold).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Zinc is an essential micro-nutrient for crops.
Its total concentration in agricultural soils is dictated by the composition of the parent rock material.

Step 2: Detailed Explanation:
In most mineral soils, the total concentration of Zinc spans a standard range from 10 to 330 ppm.
Although the total Zinc content can be relatively high, only a tiny fraction (usually less than 1--2 ppm) exists in the water-soluble or exchangeable forms that are readily available to plant roots.

Step 3: Final Answer:
The average Zinc content of mineral soils ranges between 10 to 330 ppm, which is option (A).